The proposed research involves the study of naturally occurring inhibitors of the tRNA methyltransferases which are found in normal adult tissues, but are lacking in foetal and tumor tissues. In adult liver, kidney and pancreas this inhibitor is a competing enzyme system, glycin N-methyltransferase. We have purified this enzyme to homogeneity and we are studying its properties. It is absent or greatly diminished in foetal liver or a number of hepatomas. We are also searching for analogous systems in other adult organs.